Waste processing

ABSTRACT

Disinfection of waste can be carried out by applying sufficient vacuum to suck waste pieces through a processing system, the vacuum creating a wind inside the system that sweeps up the waste pieces, suspends them in air, and keeps them separate from one another, thereby exposing substantially all surfaces of the waste pieces to the sprayed disinfectant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/857,817, filed Aug. 17, 2010, which is a continuation of U.S.application Ser. No. 12/761,850, filed Apr. 16, 2010, now U.S. Pat. No.7,776,262, which is a continuation of U.S. application Ser. No.12/571,305, filed Sep. 30, 2009, now U.S. Pat. No. 7,699,247, which is acontinuation of International Application No. PCT/US2009/042052, filedApr. 29, 2009, which claims the benefit of U.S. application Ser. No.12/120,643, filed May 14, 2008, now U.S. Pat. No. 7,534,405, U.S.application Ser. No. 12/120,771, filed May 15, 2008, now U.S. Pat. No.7,534,392, and U.S. application Ser. No. 12/121,124, filed May 15, 2008,now U.S. Pat. No. 7,568,644, each of which is hereby incorporated hereinby reference.

BACKGROUND

Waste processing for pathogen reduction has typically involved use ofheat, cooling, pressurizing, and combinations of these to disinfectwaste or place the waste in better condition for disinfection.

SUMMARY

Disinfection of waste can be carried out by first cutting the waste intosmall pieces to expose surfaces in the waste and then simultaneouslyspraying the waste pieces with disinfectant and agitating them. Thewaste pieces are agitated by applying sufficient vacuum to suck thewaste pieces through a processing system, the vacuum creating a windinside the system that sweeps up the waste pieces, suspends them in air,and keeps them separate from one another, thereby exposing substantiallyall surfaces of the waste pieces to the sprayed disinfectant.

The disclosed techniques may be employed, for example, in hospitals,where a considerable amount of the waste generated contains pathogensand so requires special handling. Systems and methods described hereinmay be employed to process such medical waste on-site and more quicklyand cheaply compared to existing systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a flowchart of a waste processing method.

FIG. 2 depicts a schematic chart for a waste processing system.

FIG. 3 illustrates an exemplary embodiment of a waste processing system.

FIGS. 4 and 4A show cross-sections taken from the embodiment of FIG. 3.

FIG. 5 shows detail of an exemplary embodiment of a cutting system.

FIG. 6 shows a cross-section taken from the embodiment of FIG. 5.

FIG. 7 shows additional detail of the embodiment of FIG. 5.

FIGS. 8-10 show detail of portions of an exemplary embodiment of afirst-stage cutting system.

FIGS. 11-13 show detail of portions of an exemplary embodiment of asecond-stage cutting system.

DETAILED DESCRIPTION

A waste processing method may include sealing infected waste inside awaste processing system, cutting the infected waste into pieces havingcross sections no larger than one square inch, thereby exposing surfacesof the waste, and agitating the waste pieces and simultaneously sprayingthe waste pieces with a disinfectant that kills pathogens on contact,thereby disinfecting the waste. The method may be carried out at roomtemperature (i.e., without adding or removing heat from the system,aside from minimal heat generated by operation of the system's movingparts) and at or below ambient pressure (i.e., at a pressure not higherthan the pressure outside the waste processing system).

FIG. 1 depicts a flowchart of a waste processing method. Contaminatedwaste (also “infected waste”), i.e., pathogen-bearing waste, is (A)isolated inside the waste processing system. Isolation will typicallyinvolve airtight and liquid-tight sealing so that contaminated wasteexposed during processing will not kick pathogens into the environmentsurrounding the system. Once the contaminated waste is sealed within thesystem, it is (B) subjected to a cutting process to reduce the waste tosmall pieces. The thickness of pieces may be substantially the thicknessof the waste as it entered the system. The cutting process may typicallyinvolve shredding and shearing operations to break the waste into smallpieces and to expose the surfaces of the waste to disinfectant. Thecutting process would typically avoid crushing the waste unlesssubsequent cutting steps would serve to re-expose surfaces obscured bythe crushing. The cutting process may typically also obliterate anyidentifying marks on the waste, such as printed characters, labels, andthe like. Following the cutting process, contaminated waste pieces mayresemble confetti.

The contaminated waste pieces are then (C) sprayed with disinfectant,typically liquid disinfectant in sufficient quantity to coat all orsubstantially all surfaces in the waste pieces. Once thus disinfected,the waste pieces may then be (D) discarded through commercial rubbishchannels.

FIG. 2 depicts a schematic chart for a waste processing system toimplement the method outlined in FIG. 1. Contaminated waste 12 isintroduced into the system by way of loading chamber 20 and is passed tocutting system 29 where it is cut into small pieces. Circulation system110 applies vacuum inside the system to suck the waste from the loadingchamber into the cutting system and thence through the rest of thesystem. If the cutting system is positioned below the loading chamber,then gravity may also help advancing the waste. Trough 60 receives thewaste pieces and disinfectant from disinfectant source 50. Vacuum fromthe circulation system creates a wind inside the system that sweeps upthe waste pieces, suspends them in the air, keeps them separate from oneanother, and agitates them in the trough and in subsequent sections ofthe system, thereby exposing as many surfaces of the waste as possibleto disinfectant sprayed on the waste. All or substantially all of thesurfaces may thereby be exposed to disinfectant.

The sprayed waste pieces are then sucked into wetting tunnel 70 and thendeposited in separator 80, in which any particulate matter that wasgenerated or liberated from the waste in the cutting process oragitation is separated from bulk waste pieces. Bulk waste passes intoreceiving bin 90, after optionally passing through a dryer (not shown),while particulate matter is directed into filter system 100, where it istrapped. Products of the waste processing system are thus bulk waste andparticulate waste.

FIG. 3 illustrates an exemplary embodiment of a waste processing system10 (with outer casing 11 removed for clarity), and FIGS. 4-4A show theindicated cross-sections. The system is enclosed in outer casing 11 for,e.g., isolating the ambient environment from noise, odors, and movingparts inside. Constituent parts of the system may be securely mounted toone or more base plates 13, 13′ for stability. Loading chamber 20includes outer door 22 and inner door 24. Outer casing 11 may have doorsufficiently in register with outer 22 to permit placement of waste 12(shown suspended in mid-air) in the loading chamber. The outer doortransitions between an open state that permits a user to place waste inthe loading chamber and a closed state that prevents access to thesystem interior in operation. The outer door may form an airtight sealin the closed state to help seal waste within the system. The inner doortransitions between a closed state that provides a surface in theloading chamber on which to place waste and an open state that permitsthe waste to leave the loading chamber for processing within the system.In some embodiments, the inner door swings up from the closed state toan “open” state in which it provides an airtight seal behind the outerdoor. The two doors may be connected with one another to providesynchronized movement; i.e., to force the inner door to be in the closedstate whenever the outer door is in the open state. The doors may bemechanically and/or electronically interlocked so that only one of themmay be in its open state at a given time. In some embodiments, a singledoor may serve as both inner door and outer door by swinging between aloading state, in which the door adopts the closed state of the innerdoor, and a sealed state, in which the door adopts the closed state ofthe outer door.

The loading chamber may also include air inlet 26 and/or detergent inlet(not shown). Air may be admitted into the loading chamber through theair inlet to help the circulation system maintain air flow through thesystem. Air discharged by the circulation system to generate vacuum maybe directed into the loading chamber through the air inlet to maintain aclosed circulation, or ambient air may be drawn into the loading chamberthrough the air inlet. Alternatively, the air inlet may be positioned atthe cutting system, described below. If the air inlet is configured todraw in ambient air, it is typically a one-way valve (such as a flapvalve) that allows only admittance of air into the system, not exhaustof air to the environment. The air inlet may also be under control of asystem controller to permit air flow only when the machine is sealed andoperating.

Cutting system 29 may include a first-stage cutting system 30 and asecond-stage cutting system 40. The first-stage cutting system receiveswaste from the loading chamber and includes cutters sized, shaped, andpositioned to cut waste into strips. The second-stage cutting systemreceives waste from the first-stage cutting system and includes cutterssized, shaped, and positioned to cut waste strips into pieces havingcross sections no larger than one square inch.

FIGS. 5-11 show an embodiment of a cutting system and component parts inmore detail.

As shown in FIGS. 5-7, first-stage cutting system 30 may includemultiple rotary cutters 31 in a fixed cutter 32. The rotary cutters havecutting tip(s) 33 and are grouped in two sets, each set turned byrespective drive shaft 35, 35 a. The two sets of cutters overlap, andthe individual rotary cutters interleave with one another; in this way,the two sets of rotary cutters cut against one another. Individualrotary cutters also interleave with multiple fins 34 on the fixedcutter. The rotary and fixed cutters are typically packed sufficientlyclosely together that they intercept and cut essentially all solidnonparticulate waste presented to them. As the waste falls between andis pulled by the cutters, the sharpened edges of the cutting tips slicethe waste into strips and shear the strips sideways, with little or nocrushing.

Thus the size of the first-stage cutting tips, and the length 135 (FIG.10) between the tips determine the size of the waste strips. In oneexemplary embodiment, the cutters are about 0.5 inch wide, the outeredge of the cutting tips are about 1 inch long and described by a circle11 inches in diameter, so that they are separated by an arc length ofabout 16 inches; thus, strips of waste up to those dimensions wouldemerge from the first-stage cutter. The size and shape of the cutterscan be modified to suit a particular purpose. To help ensure preciseshaping and sharpened edges, the contours of the cutters, especially therotary cutters, may be flame- or laser-cut from the leading edge of eachtip to the trailing edge of the other tip (distance 135 in FIG. 10).

The cutters should be made from materials hard enough to withstand theforces imposed on them during the cutting process. In a typicalapplication of processing medical waste that contains metal, plastic,and other materials, the cutters may have the dimensions given above(outer cutting edges defined by 11-inch circle, 0.5 inch thickness) andbe made from tool steel, such as oil hardening steel. One possibility isAISI O1 oil-hardening tool steel. The tool steel may be hardened (by avariety of known techniques, not just oil hardening) to a preferredhardness, such as hardness 58-60 on the Rockwell C scale (HRC 58-60).The fins of the first-stage fixed cutter may also be made from lowcarbon steel.

The drive shafts are driven by one or more motors. In the depictedembodiment, motor 36 drives belt 37 to turn an axle in first-stagegearbox 38 (such as a speed reducer), which provides rotation for driveshaft 35. The motor and subsequent linkages connecting it to the axleshould generate sufficient torque to allow the cutters to carry out thecutting process called for. In some embodiments, such as processing ofmetal and plastic medical waste, torque developed by the axle may be inthe range of 500 foot-pounds to 2,000 foot-pounds, 750 foot-pounds to1,500 foot-pounds, 900 to 1,200 foot-pounds, 950 to 1,050 foot-pounds,and/or about 1,000 foot-pounds. In some embodiments, force exerted bythe cutter tips on the material being processed may be in the range of1,000 pounds to 4,000 pounds, 1,500 pounds to 3,000 pounds, 1,900 poundsto 2,400 pounds, 2,000 pounds to 2,300 pounds, and/or about 2,200pounds. In the case of cutters having outer cutting edges defined by an11-inch circle (0.458 feet from center of rotation to tip), amotor-linkage arrangement generating about 1,000 foot-pounds of torquewould present about 2,200 pounds of force at the tips. In oneembodiment, a 5 HP motor operating at 1,750 rpm (such as a RelianceP18G4903 or Baldor M3665T) produces about 15 foot-pounds of torque,which when coupled by a belt and pulleys with a 2.75 diameter ratio to a25×speed reducer (such as a Dodge TXT325-BT) will produce about 1,000foot-pounds of torque at an axle rotating at about 25 rpm and driven bythe reducer. An 11-inch cutter rotating on the axle will deliver about2,200 pounds of force at its tips.

Drive shafts 35 and 35 a are coupled by intermeshing gears 39 and 39 a,thereby providing rotation for drive shaft 35 a. As shown, the gears maybe of different sizes (or otherwise differing), so as to have a gearratio of other than 1:1, thereby causing the two drive shafts to rotateat speeds different from one another (which may improve cuttingefficiency by constantly confronting waste with different cutterprofiles). Alternatively, the gears may be sized and shaped to maintainthe same speed of the two drive shafts. In some embodiments, the twoshafts may be driven by two separate motors, at identical or differentspeeds.

The fixed cutter 32 may be affixed to, or integrally formed with, one ormore brackets 122. The bracket(s) may be in turn attached to anadditional support 120 that is affixed to a base plate. The bracket(s)and support provide stability and also vertical positioning of thefirst-stage cutting system relative to other system components.

In normal cutting operation, the rotary cutting blades rotate inwardly,i.e., so that the cutting tips rotate toward one another on the side ofthe first-stage cutting system to which waste is initially presented(the top side in the embodiment shown). The rotary blades may be capableof reverse motion for various purposes, such as clearing jams.

FIG. 5 also shows external features of second stage cutter 40, includingmotor 46 that drives second-stage drive shaft 45 by way of belt 47 andsecond-stage gearbox 48. The second-stage motor may have similarproperties as the first-stage motor, discussed above.

FIG. 6 shows the cross-section indicated in FIG. 5 to illustrate furtherdetails of the depicted embodiment. Transition zone or chute 28 ispositioned between the first- and second-stage cutting systems andchannels waste material from the first-stage cutting system to thesecond-stage cutting system. The chute also provides a space fortemporarily holding waste material between the cutting systems. Thesecond-stage cutting system includes second-stage rotary cutter 41 withmultiple cutting tips 43, and second-stage fixed cutter 42.

The second-stage cutting system may also include comb 44 that agitateswaste as it is presented to the second-stage cutters. The comb shuttlesoblique to the motion of the rotary cutter (for example, side-to-sidealong the rotary cutter's axis of rotation) and may be driven byrotational energy supplied by second-stage drive shaft 45 through belt128, gearbox 126, and axle 124, although other power schemes arepossible, such as a dedicated motor. The comb may have a variety ofshapes; the illustrated embodiment has multiple sharp ridges and curvedgrooves between the ridges; the ridges may be blunt, and the grooves mayhave straight sides, somewhat like the second-stage fixed cutter 41. Thecomb may be made, for example, using steel, such as low carbon steel,optionally with a black oxide finish.

Trough 60 is positioned below the second-stage cutting system to receivethe completely cut waste.

FIG. 7 shows the embodiment of FIG. 5 from a different perspective tohelp illustrate various features.

FIG. 8 shows detail of the first-stage fixed cutter 32. It definesthrough-holes 130, 130 a for passage of the first-stage drive shafts.Multiple fins 34 extend inwardly from the sides of the fixed cutter andare separated from one another by spaces 34 a. The bottom of the fixedcutter defines a gap 132 to allow shredded waste to fall out of thefirst-stage cutting system; flush ends 134 of the fins may help in partto define the gap.

FIG. 9 shows another view of the first-stage fixed cutter 32, now withthe rotary cutters 31 in position. The rotary cutters fit intorespective spaces 34 a, and the two sets of rotary cutters interleavewith one another. Fins 34 on the left side of the fixed cutter arestaggered with respect to those on the right side.

FIG. 10 shows an exploded view of one set of first-stage rotary cutters(i.e., from the left or right side of the fixed cutter). Each cutterdefines a central hole 136 through which the drive shaft passes. Eachcutter further defines or includes a feature, such as the illustratedkeyway 138, that corresponds to a complementary feature on the driveshaft (e.g., a key or rail, not shown in the drawings or represented inthe appended computer program listing) to prevent rotation of thecutters relative to the drive shaft. In the depicted embodiment, thefeatures on the cutters are oriented at positions different from oneanother such that the various cutters are rotationally fixed to thedraft shaft with their cutting tips 33 at different angles; such anglevariation among cutters may increase cutting efficiency. The slight hookshape to the cutting tips can help pull waste into the cutting system,in synergy with the vacuum applied by the circulation system. The hookson one set of rotary cutters rotate toward the other set, andvice-versa.

FIGS. 11-13 provide greater detail of the second-stage cutting system40.

As shown in FIG. 11 and noted previously, drive shaft 45 is powered bymotor 46 (not shown) through gearbox 48 and turns second-stage cutter41. Second-stage fixed cutter 42 defines multiple fins 144 separated byspaces 146; the rotary cutters turn in the spaces to shear the shreddedwaste from the first-stage cutting system. Comb 44 shuttles side-to-sideto help agitate and position waste strips for shearing; the comb ispowered either through a linkage (i.e., axle 124, gearbox 126, and belt128 driven by drive shaft 45) to motor 46 or by another motor. Linearmovement of the comb may be obtained by using a screw drive,rack-and-pinion system, linear friction actuator, or other linkage forconverting rotational motion to linear motion. Disinfectant supply lines63 conduct disinfectant to trough 60 (not shown); individual feederlines 64 may be provided to direct disinfectant into disinfectant inlets62 (not shown).

FIG. 12 provides a close-up view of a portion of the second-stagecutting system, with side plate 156 removed for clarity. Second-stagerotary cutter 41 has multiple cutting tips 43 protruding from itssurface, which are sized, shaped, and positioned on the cutter to be inregister with spaces 146 on the second-stage fixed cutter 42. Cutter 41has a tubular shape defining a bore 140 through which drive shaft 45passes. The cutter further defines or includes a feature, such as theillustrated keyway 142, that corresponds to a complementary feature onthe drive shaft (e.g., a key or rail 158, not represented in theappended computer program listing) to prevent rotation of the cuttersrelative to the drive shaft, largely as described earlier for thefirst-stage cutters.

Cutting tips 43 are in register with corresponding spaces 146 and arecomplementarily shaped to the grooves. In the depicted embodiment, thetips are chamfered (i.e., they taper toward their free ends), and thegrooves are chamfered at the same angle. As a result, the clearancebetween the tips and the grooves can be made quite small, such as in therange of 0.00005 inch to 0.01 inch and typically 0.001 (one-thousandth)inch. Such small clearance helps ensure that waste entering the secondstage cutting system has nowhere to go but between the cutters. As thewaste is forced between the cutters, the sharpened edges of the cuttingtips slice the waste longways and shear it sideways, with little or nocrushing.

Thus the size of the second-stage cutting tips, and the length 154 (FIG.13) between the tips determine the final maximum size of the wastepieces. In the depicted embodiment, there are 12 teeth around thecircumference of the cutter, which has a diameter d of about 5 inches;the tips have a separation length 154 of about ⅕ d (1 inch) and a widthat the free end of about 1/20 d (0.25 inch). The fixed cutter hassimilar dimensions to the tips, within small tolerances; as a result,the dimensions given above are the theoretically maximum dimensions ofwaste pieces emerging from the cutting system. In practice, waste stripsand pieces tumble about as they pass through the cutting system and arecut multiple times, so that the pieces have final dimensions no largerthan smallest cutting dimension (0.25 inch in the example given here).These relative and absolute dimensions are provided for illustrativepurposes only and are not essential; relative dimensions betweendiameter, separation, and width may vary.

Cutter 41 is shown as a single piece, but it could be replaced by a setof disks, each with one or more ranks of teeth about theircircumferences.

The rotary and fixed cutters of the second stage cutting system may bemade of similar materials as those, such as tool steel, in particular,AISI O1 oil hardening tool steel hardened to HRC 58-60.

FIG. 13 shows the cut section indicated in FIG. 11. Fixed cutter 42 androtary cutter 41 interact in arcuate side zones 150, 152; space abovethe rotary cutter is free in order to provide a clear path for wastestrips emerging from the first-stage cutting system and transition zone;space below the rotary cutter is free to provide a clear path for wastepieces to fall into trough 60.

One or more agitators can be positioned between the loading chamber, thefirst-stage cutting system, and the second-stage cutting system tojostle waste as it passes through and dislodge jams. A metering devicemay also be positioned between the stages to help feed waste into thesecond-stage cutting system at a regulated rate.

Waste exits the cutting system in the form of small pieces, typicallyhaving cross-sections no larger than one square inch (such as one inchby one inch square), 0.25 in² (such as half-inch by half-inch square),and/or 0.0625 in² (such as quarter inch by quarter inch square). Thecutters of the cutting system are sized, shaped, and positioned in orderto cut down waste to the desired size. The cutter arrangement,therefore, can help ensure that no piece of waste has any dimensionlarger than a set limit, such as one inch, 0.5 inch, or 0.25 inch.

Waste leaves the cutting system and passes into a trough 60, wheredisinfectant from disinfectant source 50 is sprayed through disinfectantinlets 62, such as jets, onto the waste. As noted previously, agitationof waste by the circulation system 110 helps expose all facets of thewaste pieces to the disinfectant. The circulation system will typicallyapply sufficient vacuum to suck waste through the system at least 75miles per hour. For example, in the illustrated embodiment, in whichwetting tunnel 70 extends vertically several feet, such pressureovercomes gravity to ensure that material passes through the wettingtunnel without falling to the bottom.

The disinfectant will typically be a liquid, although it may also be agas or a powder. The disinfectant may be an alkaline solution, such asan aqueous alkaline solution. The solution may have a pH of at least 12.In one embodiment, the disinfectant is a pH 12 or greater aqueoussolution of calcium oxide (CaO); a 10% solution (“milk of lime”) istypically used. A principal source of CaO is kiln dust. Because CaOdegrades rapidly on exposure to air and moisture, it may be stored indry powder form and put in solution (such as mixing with water suppliedfrom line 14) shortly before being sprayed into the waste processingsystem.

Sprayed waste pieces are sucked from the trough into wetting tunnel 70,where agitation continues. Additional jet(s) may be provided in thewetting tunnel to aid the wetting and disinfection process. The lengthof the wetting tunnel is not critical; disinfection occurs substantiallyon contact. In some embodiments, therefore, the wetting tunnel may beomitted, and waste passes from the trough to the separator.

Separator 80, such as a cyclone separator, may be used to divide thedisinfected waste by size into pieces large enough to settle quicklyinto receiving bin 90 (such as into refuse bag 91) and particulatematter that will not settle so readily. The large pieces, constitutingthe bulk waste, typically fall by gravity out of the separator in thereceiving bin, while particulate matter remains suspended in the airstream generated by the circulation system and directed into filtersystem 100. If the input waste includes liquid, the liquid can similarlyfall out of the separator into a refuse bag.

The filter system 100 can include a number of components, including abag filter, an odor filter, a HEPA filter, and/or a noise-reductionmuffler. The bag filter can be used to trap the vast majority of theparticulate waste; little waste, except the finest particulate matter,may escape the bag filter. The odor filter may be used to capture gasesin the air to reduce bad odors. The HEPA filter may be a very finefilter that will capture particulate matter, if any, that evaded the bagfilter. The main vacuum source for the circulation system may bepositioned among the filter system components, for example, downstreamof the bag filter and upstream of other filter components.

The waste processing system may include a controller, such as acomputer, that provides a command console for an operator. Thecontroller may also record information about operational parameters,such as run times, waste throughput, operator identification, and statusof system components, such as empty/full status of the loading chamber,cutting system, disinfectant source, receiving bin, and filter system.The controller can also receive sensory data from within the system,such as weight scale(s) in the loading chamber and receiving bin tomonitor accumulation of waste, and torque and/or motion sensors in thecutting system to detect jams. The controller can command operation ofthe cutting system and operate it in a variety of modes depending ontype of waste input or need to remove a jam.

In one exemplary embodiment, a waste processing method includes (a)placing infected waste in the loading chamber; (b) closing the loadingchamber door, thereby sealing the infected waste inside the wasteprocessing system; (c) opening the trap door, thereby allowing theinfected waste to leave the loading chamber and contact the first-stagecutting system; (d) actuating the circulation system to apply sufficientvacuum through the filter system, the wetting tunnel, the trough, thesecond-stage cutting system, the first-stage cutting system, and theloading chamber to suck waste therethrough; (e) operating the cuttingsystem on infected waste to cut it into pieces having cross sections nolarger than one square inch, the pieces advancing to the trough; (f)spraying disinfectant into the trough as the infected waste pieces passtherethrough, thereby coating the waste pieces with disinfectant anddisinfecting them; (g) sucking the waste pieces through the trough,through the wetting tunnel, and into the separator; (h) separatingmaterial received by the separator into disinfected particulate wastematter and disinfected bulk waste matter; (i) advancing bulk wastematter into the receiving bin; and (j) trapping particulate waste matterin the filter system.

The various components of the waste processing system described hereinmay be used individually for other purposes. In particular, thedisclosed cutting system may be used for other applications requiringsize reduction of input material. For example, the cutting system may beused to reduce the size of waste that does not require pathogenreduction or has already been treated for pathogen reduction. Thecutting system may be used for shredding and shearing a wide variety ofmaterials, such as metal, plastic, paper, glass, wood, euthanizedanimals, animal waste- and by-products, organic matter, etc. Exemplaryuses include preparing materials for recycling, for space-efficientdisposal, for use as filler, and for obliterating identifyingcharacteristics.

While the dimensions of objects in the drawings reflect those ofmechanical drawings and a prototype prepared to the inventor'sspecifications, they (and indeed all relative and absolute dimensionsdisclosed herein) are provided for illustrative purposes only and arenot intended to be limiting unless expressly claimed.

1. A method of disinfecting waste, comprising simultaneously: agitatinginfected waste pieces by applying sufficient vacuum to sweep theinfected waste pieces up in a wind that suspends the infected wastepieces and keeps the infected waste pieces separate from one another,thereby exposing substantially all surfaces of the infected waste piecesto a sprayed disinfectant; and spraying the waste pieces with a liquiddisinfectant that kills pathogens on contact, thereby coating the wastepieces with disinfectant and disinfecting them; wherein the steps arecarried out without adding heat to the waste processing system, withoutremoving heat from the waste processing system, and without increasingpressure inside the waste processing system.
 2. The method of claim 1,further comprising cutting infected waste into the infected waste pieceshaving cross sections no larger than one square inch, thereby exposingsurfaces of the waste, prior to agitating and spraying.
 3. The method ofclaim 2, further comprising sealing the infected waste inside a wasteprocessing system that comprises: a cutting system that receives wasteand comprises cutters sized, shaped, and positioned to cut waste intopieces having cross sections no larger than one square inch; a troughthat receives waste pieces from the cutting system and that comprisesone or more disinfectant inlets; a source of disinfectant that is influid communication with the one or more disinfectant inlets to spraydisinfectant onto waste pieces in the trough; and a circulation systemthat applies the vacuum to suck waste through the waste processingsystem.
 4. The method of claim 3, wherein the waste processing systemfurther comprises a wetting tunnel that receives disinfectant-sprayedwaste pieces from the trough, and wherein the waste pieces are agitatedin the wetting tunnel.
 5. The method of claim 5, wherein the wettingtunnel comprises one or more disinfectant inlets to spray disinfectantonto waste pieces in the wetting tunnel, and the method furthercomprises spraying the waste pieces with a disinfectant while the wastepieces are agitated in the wetting tunnel.
 6. The method of claim 1,wherein the disinfectant comprises an alkaline solution.
 7. The methodof claim 6, wherein the alkaline solution is prepared using kiln dust.8. The method of claim 7, wherein the alkaline solution has a pH of 12or greater.
 9. The method of claim 6, wherein the alkaline solutioncomprises a 10% aqueous solution of calcium oxide.
 10. The method ofclaim 1, wherein the disinfectant is provided in dry powder form andmixed with water to form an aqueous solution shortly before beingsprayed onto the waste pieces.
 11. A system for disinfecting waste, thesystem comprising: a trough that receives waste pieces and thatcomprises one or more disinfectant inlets; a source of disinfectant thatis in fluid communication with the one or more disinfectant inlets tospray onto the waste pieces a liquid disinfectant that kills pathogenson contact; and a circulation system that applies sufficient vacuumthrough the cutting system and the trough to suck waste therethrough,agitate the waste pieces, and sweep the waste pieces up in a wind thatsuspends the waste pieces and keeps the waste pieces separate from oneanother as the waste pieces are being sprayed with the disinfectant,thereby exposing substantially all surfaces of the waste pieces to thedisinfectant, coating the waste pieces with disinfectant, anddisinfecting the waste pieces.
 12. The system of claim 11, furthercomprising a loading chamber into which uncut waste is received.
 13. Thesystem of claim 12, wherein the loading chamber comprises an outer doorand an inner door, the outer door transitionable between an open stateto allow loading of waste into the loading chamber and a closed state toseal waste within the system, and the inner door transitionable betweena closed state to provide a surface in the loading chamber and an openstate allowing waste to advance from the loading chamber.
 14. The systemof claim 13, wherein the inner door and the outer door are interlockedwith one another so that only one of them may be in an open state at agiven time.
 15. The system of claim 11, further comprising a wettingtunnel that receives disinfectant-sprayed waste pieces from the troughand extends upward from the trough, wherein the waste pieces areagitated in the wetting tunnel by operation of the circulation system,and wherein the circulation system provides sufficient vacuum toovercome gravity to ensure that the waste pieces pass through thewetting tunnel without falling back to the trough.
 16. The system ofclaim 15, further comprising a separator positioned to receive wastefrom the wetting tunnel.
 17. The system of claim 16, wherein theseparator comprises a cyclone separator, and wherein the system furthercomprises (a) a receiving bin positioned to receive bulk waste pieces,and (b) a filter to trap particulate matter from the cyclone separator.18. The system of claim 12, wherein the circulation system applies thevacuum to the loading chamber.
 19. The system of claim 12, wherein theloading chamber comprises a door transitionable between a loading stateto provide a surface in the loading chamber on which to place waste, anda sealed state to seal waste within the system.